The human T-cell leukemia (lymphotropic) virus (HTLV-III) is a retrovirus which carries its genetic code on RNA. When a retrovirus infects a host cell, a DNA copy of its genome is integrated into the chromosome of its host. With some retroviruses, the DNA is integrated into the host cell's chromosomes in the form of a sequence known as a provirus. The DNA copy of the retrovirus' genetic code is synthesized by a viral enzyme called RNA dependent DNA polymerase, or reverse transcriptase. The host cells transcribe the DNA of the viral gene and synthesize the proteins encoded by the virus, which are then assembled into new viruses.
The HTLV-III RNA genome is similar to those of other retroviruses and contains at least (i) a gag gene that encodes the internal structural (nucleocapsid or core) proteins, (ii) a pol gene that encodes the reverse transcriptase, and (iii) any env gene that encodes the envelope glycoproteins of the virus. HTLV-III contains additional genes including those designated tat, sor, and 3'-ORF.
The complete DNA nucleotide sequence for HTLV-III has been reported in the literature by several researchers: Ratner et al., Nature, 313:277-284 (1985); Muesing et al., Nature, 313:450-485 (1985); Sanchez-Pescador et al, Science, 227:44-492 (1985); and Wain-Hopsin et al, Cells, 40:9-17 (1985).
Others have shown that the entire HTLV-III envelope protein can be used for diagnosis of the HTLV-III virus. Allan et al., Science, 228:1091-1094 (1985); Barin et al., Science, 228: 1094-1096 (1985); and Veronese et al., Science, 229: 1402-1405 (1985).
Molecular cloning of portions of the virus sequence has been achieved, as described in Ratner et al., supra; Chang et al., Bio/Technology, 3: 905-909 (1985); Chang et al., Science, 228: 93-96 (1985); and Crowl et al., Cell, 41: 979-986 (1985). These clones provide material for analysis of possible polypeptide epitopes on the HTLV-III viral surface against which the immune system can mount an antibody reaction. Identification of these epitopes is important in the development of sensitive and rapid methods for the diagnosis of AIDS.